Study of rapid carrier capture and relaxation in InAs/GaAs heterostructures

The rapid carrier capture and relaxation processes in InAs/GaAs quantum dot s were studied at 77K by using a simple degenerate pump-probe technique. A rising process was observed in the transient reflectivity, following the in itial fast relaxation associated with GaAs bulk matrix, and this rising pro cess was assigned to be related to the carrier capture from the GaAs barrie rs to InAs layers. The assignment was modeled using Kramers-Kronig relation . By analyzing the rising process observed in the transient reflectivity, t he carrier capture time constants were obtained. The measured capture times decrease with the increase of carrier concentration.